build: move e2e dependencies into e2e/go.mod

Several packages are only used while running the e2e suite. These
packages are less important to update, as the they can not influence the
final executable that is part of the Ceph-CSI container-image.

By moving these dependencies out of the main Ceph-CSI go.mod, it is
easier to identify if a reported CVE affects Ceph-CSI, or only the
testing (like most of the Kubernetes CVEs).

Signed-off-by: Niels de Vos <ndevos@ibm.com>

e2e/vendor/github.com/onsi/gomega/CONTRIBUTING.md

@@ -0,0 +1,14 @@
+# Contributing to Gomega
+
+Your contributions to Gomega are essential for its long-term maintenance and improvement.  To make a contribution:
+
+- Please **open an issue first** - describe what problem you are trying to solve and give the community a forum for input and feedback ahead of investing time in writing code!
+- Ensure adequate test coverage:
+    - Make sure to add appropriate unit tests
+    - Please run all tests locally (`ginkgo -r -p`) and make sure they go green before submitting the PR
+    - Please run following linter locally `go vet ./...` and make sure output does not contain any warnings
+- Update the documentation.  In addition to standard `godoc` comments Gomega has extensive documentation on the `gh-pages` branch.  If relevant, please submit a docs PR to that branch alongside your code PR.
+
+If you're a committer, check out RELEASING.md to learn how to cut a release.
+
+Thanks for supporting Gomega!